1. Technical Field
This application generally relates to memory usage, and more particularly to techniques used for memory partitioning and management.
2. Description of Related Art
Computer systems may include different resources used by one or more host processors. Resources and host processors in a computer system may be interconnected by one or more communication connections. These resources may include, for example, data storage devices such as those included in the data storage systems manufactured by EMC Corporation. These data storage systems may be coupled to one or more host processors and provide storage services to each host processor. Multiple data storage systems from one or more different vendors may be connected and may provide common data storage for one or more host processors in a computer system.
A host processor may perform a variety of data processing tasks and operations using the data storage system. For example, a host processor may perform basic system I/O operations in connection with data requests, such as data read and write operations.
Host processor systems may store and retrieve data using a storage device containing a plurality of host interface units, disk drives, and disk interface units. Such storage devices are provided, for example, by EMC Corporation of Hopkinton, Mass. and disclosed in U.S. Pat. No. 5,206,939 to Yanai et al., U.S. Pat. No. 5,778,394 to Galtzur et al., U.S. Pat. No. 5,845,147 to Vishlitzky et al., and U.S. Pat. No. 5,857,208 to Ofek. The host systems access the storage device through a plurality of channels provided therewith. Host systems provide data and access control information through the channels to the storage device and storage device provides data to the host systems also through the channels. The host systems do not address the disk drives of the storage device directly, but rather, access what appears to the host systems as a plurality of logical disk units, logical devices or logical volumes. The logical disk units may or may not correspond to the actual physical disk drives. Allowing multiple host systems to access the single storage device unit allows the host systems to share data stored therein.
Memory may be included within a data storage system and, more generally, in any type of system or device using a processor. The memory may be configured for use with one or more processors, or directors, for various purposes such as caching. In connection with data storage systems such as by EMC Corporation, various types of directors or adapters may be implemented as a processor, or, more generally, a component that includes the processor. Examples of directors are disk adapters (DAs), host adapters (HAs) and the like. In one arrangement, a first set of one or more memory boards may be configured to include only global memory. The first set of boards does not include any directors. A second set of one or more boards may be configured to include directors and not any global memory. Memory, such as of the first set of boards, designated as global memory is accessible for use by any director included in the second set of boards. In the foregoing arrangement, the global memory is configured to be physically segregated on separate boards from other boards including the directors which access the global memory.